Bicycle Mechanics - Question about running single chainring

Just put a bike together with one ring up front, so I didn't bother putting the FD back on. Do I need a chaincatcher/keeper whatever or anything up there to make sure the chain stays on? I've only ridden it once, and haven't put a shifter on yet so it's a basically a SS at the moment, and I don't know if when I start shifting whether it'll start throwing the chain or not?

Do you still have a rear derailer and cassette? Generally a 1x* doesn't need anything up front, but it is still possible to derail the front. Putting the front derailer back on and leaving it locked in position isn't a terrible idea. They also make chainkeepers for this, as you mentioned. My advice would be to try it first and see if you have any issues. No point in having more stuff on there than necessary.

It depends. I find that on a geared bike a 1x setup the chain can be thrown fairly easily if it has a ramped chainring. My wifes 1x has a downhill ring and it never throws, mine is ramped and comes off. On a s/s I found no issues of throwing the chain with either a s/s ring or a ramped one. As long as the chain line is straight and taunt, no worries.

It's got a 7 speed freewheel, and it's a ramped chainring. I'll give it a whirl as it is once I find the shifter I want and see how it acts. As said above, I don't want anymore stuff than I need on it. A downhill ring eh? I was going to make it into a SS, but would've had to buy parts to make the chainline correct. Already had everything for a multispeed, so cheaper is better :)

On the road and for most situations a single ring shouldn't need any help keeping a chain on. After all, when not shifting, your chain stays on without rubbing or being helped in any way by the FD.

That's the theory, and for smooth roads it will work for you 99.9% of the time. But if your single ring was made to work as one of two or three, it probably has shift gates (cut down teeth) who'se purpose is to make it easier for the chain to derail to the next ring, so don't be shocked if it derails to your BB shell.

Also if riding off road, or on bad roads (some near me are worse than off road) the bouncing and jolting can move the chainring out from under the chain and cause derailing. You might not notice or hear the FD catching the chain on your double or triple crank when that happens.

My advice is to use a non-gated ring, and see if it works for you. If not use a chain keeper, or front derailleur locked in place as a safety net. For very bouncy conditions you might need one of those roller chain keepers, or a pair of blank rings on either side to keep it on.

I would buy something like an MRP 1.x chain guide. I built up a 1x9 bike last year. First I tried using a nine-speed chain and a ramped chainring. Then I put on a non-ramped chainring. The solution that actually worked was to install the chain guide.

As a bonus, the chain guide *looks* cool too. :thumb:

If its a mountain bike, then chain guide. If its a road/round town bike, then no chain guide.

The front mech does play a part in preventing chain unmounting, usually when you hit a bump.
Modern chains have a lot of lateral flex so I would always use a chain-keeper of some sort on 1xx systems. My 1x7 system needed one.

Singlespeed and hub gear setups can use unramped cogs which hold onto chains better. Singlespeed chains also have less flex.

I run 1x8 on my hybrid and 1x10 on my road bike. On both bikes I have a single-speed chain ring. And, on both bikes, unless I was really, really careful I used to drop my chain going over certain bumps on my commute.

With the hybrid I solved the problem with the addition of a third eye chain watcher (http://www.rei.com/product/670913/third-eye-chain-watcher). On the road bike, I stop the chain from dropping with a Paul Component Chain Keeper (http://www.paulcomp.com/chainkeeper.html).

.. consider a non ramped chainring .. the engineers worked to make the chain
More willing to shift away.
You don't want it to do that any more.

Just to be clear, these guys are talking about ramped rings vs ramped cassettes/freewheels.

I would personally run a chain catcher and an outer chainring that have the teeth filed off.

You want your chainline to be perfect with the 4th cog in back. Chain tension is also important.

Thanks for all the info fellas :) Looks like a chaincatcher of some sort it is :) And will look for a non-ramped chainring if I have a problem after that.

Here's the bike since I didn't give enough info originally. And it's got a new chain on it now, that short one was just to give the bike an initial ride and see how it felt. Time to finish it up now :)

http://i82.photobucket.com/albums/j265/jbrow1/bike028-1.jpg

Mine is 1 x 7. I originally had a ramped chainring, and dropped the chain constantly. I switched to a single-speed chainring (Surly) and that took care of it - no need for a 'guide'. Ramped chainrings are designed to give up the chain easily in response to a nudge from the derailleur. SS chainrings have big tall teeth that hold the chain.

in addition to the above-recommended non-ramped chainring (the Surly stainless is golden), several other things also helped me when i ran my 1x9 (YMMV):
1. make sure your chain has no stiff/stuck segments; if the chain doesn't bend effortlessly while going around the ring, it will likely come off;
2. pinned chains (i.e., rivet) tended to perform better for me than masterlink chains (usually because of #1 above);
3. keep the chain clean and well-lubed always (otherwise #1);
4. if you notice a particular problem spot when shifting (e.g., from 2nd to 1st gear), ease up on the pedals when shifting on that spot---my chain had a tendency of coming off at the bottom of the chainring (chainsuck) due to this and #1 above;

In "The Dancing Chain (http://www.thedancingchain.com/)" there is a period line drawing of the 1x3 Rectiligne-Caminade derailleur drivetrain on a 1933 bike. It's got a front chain guide.

They'd already learned.